The invention relates generally to lock mechanisms, and more particularly to a locking mechanism that achieves its locked state only after immersion in water.
Some systems used in maritime environments are required to first sense the presence of water and then, only after water is sensed, actuate the elements of a device""s operational sequence. That is, the system must be incapable of in-air operation and guarantee operation only after entering a water environment. For example, an underwater fuze might have an arming sequence that must be started only in water. Typically, the arming sequence includes a device that must sense the presence of water and then set and lock in a certain position for the arming sequence to be initiated. The device used to perform this function should be reliable, be capable of operation in shallow or deep water, be capable of operation in muddy or otherwise dirty water, and have a long shelf life.
Accordingly, it is an object of the present invention to provide a mechanism that sets and locks itself in a given position only after immersion in water.
Another object of the present invention is to provide a water-activated locking mechanism that is simple and reliable.
Still another object of the present invention is to provide a water-activated locking mechanism that operates in any water environment regardless of water depth or cleanliness of the water.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a water-activated locking mechanism has a housing with a chamber formed therein. At least one port communicates with the chamber for allowing water to enter when the housing is immersed in water. Compressed water-absorbent fibers that can be in the form of pellets are housed in the chamber. A piston assembly is slidably mounted in the housing and is biased towards the chamber. A first end of the piston assembly resides in the chamber. The piston assembly has an indented portion thereof between the first end and a second end of the piston assembly. A pin assembly is slidably mounted in the housing at an angle relative to the piston assembly. The pin assembly is biased towards the piston assembly with one end of the pin assembly contacting the indented portion of the piston assembly to define a first position of the pin assembly. When the housing is immersed in water so that water enters the port(s) thereof, the compressed water-absorbent fibers undergo expansion and apply a force to the first end of the piston assembly. This brings about sliding movement of the piston assembly within the housing and causes the indented portion of the piston assembly to move past the pin assembly. When the first end of the piston assembly aligns with the end of the pin assembly, the pin assembly is moved and locked in a second position.